HaloRay 4.1.0

Changed

• Changed equation used to calculate index of refraction from one provided in Stanley Gedzelman's paper Simulating Rainbows and Halos in Color to a polynomial fitted to data provided by Warren and Brandt in their paper Optical Constants of Ice from The Ultraviolet to The Microwave, which is what HaloPoint 2.0 uses
• HaloRay now remembers which folder you opened last when loading or saving files like simulation parameter files or images, and opens the file dialog picker in that same folder the next time